Sealants, adhesives and similar flowable or moldable components are often used on various parts of assemblies which are assembled on a moving production line. Such sealants are used, for example between internal mating surfaces of automobile body parts to achieve adhesion, water tight seal and vibration isolation between these parts. Often times, the body parts are formed in a manner to specifically receive the sealants in certain locations; for example, the interior roof panel of an automobile may be formed with one or more channels therein, of various cross-sectional configurations, to receive a bead of sealant which adheres to and forms a seal with the outer roof panel of the automobile. The bead of sealant is preferably applied within the channel such that it initially possesses a cross-section similar to that of the channel but is expandable so that it fills the entire channel and moves into contact with a mating body part to form a proper seal.
In the past, sealants of the type described above have been sometimes applied to the parts on an off-line basis. That is to say that the sealants have been either preformed and/or applied to the parts which are stock piled and later installed into the assembly on the production line.
In some cases, attempts have been made to apply sealants on body parts directly on the assembly line by pumping the sealant from a bulk supply through a fluid line to a nozzle which a production worker manually manipulates to lay a bead of sealant into a predesired location on a body part. On-line pumping of sealants in this manner has not been entirely successful for a number of reasons. First, most "pumpable" sealants do not cure until they are heated when the assembled part is introduced into an oven on the assembly line. This delay in curing is undesirable for a number of reasons. Pumpable type sealants must possess requisite characteristics to allow them to flow through a long feed tube to the production line, yet these same characteristics often reduce the sealers performance in the areas of strength, shock vibration, etc. Also, the equipment needed to pump flowable sealants, and particularly those used to pump hot sealants can result in equipment problems, since those that have quick curing times commence curing (and thus altering their physical characteristics) as they flow through the supply tube to the exit nozzle.
Others in the past have devised extruders of various types which may be considered as portable. However, known portable extruders had been limited in their use to relatively flowable, low viscosity materials which are not suitable as sealants and adhesives in many applications, such as the assembly of automobile body parts. Automobile assembly operations require extremely high performance sealants and adhesives which typically possess extremely high viscosity and very short curing times.
There is therefore a need in the art for a method and apparatus for extruding in-place high viscosity, high performance flowable materials, in place in predetermined locations on a part substrate.